PYTHONDONTWRITEBYTECODE documentation is incorrect

Documentation

PYTHONDONTWRITEBYTECODE is documented in Doc/using/cmdline.rst as:

If this is set to a non-empty string, Python won't try to write .pyc files on the import of source modules.

This is incorrect. The variable is obtained in Python/initconfig.c as:

    int dont_write_bytecode = 0;
    _Py_get_env_flag(use_env, &dont_write_bytecode, "PYTHONDONTWRITEBYTECODE");
    if (dont_write_bytecode) {
        config->write_bytecode = 0;
    }

and _Py_get_env_flag reads the environment variable value as integer, treating non-integer string as 1. Specifically, this means that PYTHONDONTWRITEBYTECODE=0 will not suppress writing .pyc files, even though the environment variable is assigned a non-empty string "0".

Linked PRs

• gh-143144

從 Doc/using/cmdline.rst 開始，將文件中描述的行為與 Python/initconfig.c 進行比較，尤其要注意 issue 中所示的 _Py_get_env_flag 呼叫。更新環境變數描述，使其整數解析和 PYTHONDONTWRITEBYTECODE=0 的行為準確無誤；當措辭與實作一致時，文件就完成了。